fix!: no-unused-vars varsIgnorePattern behavior with catch arguments

docs/src/rules/no-unused-vars.md

@@ -135,7 +135,7 @@ By default this rule is enabled with `all` option for variables and `after-used`
 ```json
 {
     "rules": {
-        "no-unused-vars": ["error", { "vars": "all", "args": "after-used", "ignoreRestSiblings": false }]
+        "no-unused-vars": ["error", { "vars": "all", "args": "after-used", "caughtErrors": "none", "ignoreRestSiblings": false }]
     }
 }
 ```
@@ -144,7 +144,7 @@ By default this rule is enabled with `all` option for variables and `after-used`
 
 The `vars` option has two settings:
 
-* `all` checks all variables for usage, including those in the global scope. This is the default setting.
+* `all` checks all variables for usage, including those in the global scope. However, it excludes variables targeted by other options like `args` and `caughtErrors`. This is the default setting.
 * `local` checks only that locally-declared variables are used but will allow global variables to be unused.
 
 #### vars: local
@@ -164,7 +164,7 @@ some_unused_var = 42;
 
 ### varsIgnorePattern
 
-The `varsIgnorePattern` option specifies exceptions not to check for usage: variables whose names match a regexp pattern. For example, variables whose names contain `ignored` or `Ignored`.
+The `varsIgnorePattern` option specifies exceptions not to check for usage: variables whose names match a regexp pattern. For example, variables whose names contain `ignored` or `Ignored`. However, it excludes variables targeted by other options like `argsIgnorePattern` and `caughtErrorsIgnorePattern`.
 
 Examples of **correct** code for the `{ "varsIgnorePattern": "[iI]gnored" }` option:
 
@@ -333,7 +333,7 @@ Examples of **correct** code for the `{ "caughtErrorsIgnorePattern": "^ignore" }
 ::: correct
 
 ```js
-/*eslint no-unused-vars: ["error", { "caughtErrorsIgnorePattern": "^ignore" }]*/
+/*eslint no-unused-vars: ["error", { "caughtErrors": "all", "caughtErrorsIgnorePattern": "^ignore" }]*/
 
 try {
     //...

docs/src/use/migrate-to-9.0.0.md

@@ -28,6 +28,7 @@ The lists below are ordered roughly by the number of users each change is expect
 * [Case-sensitive flags in `no-invalid-regexp`](#no-invalid-regexp)
 * [Stricter `/* exported */` parsing](#exported-parsing)
 * [`"eslint:recommended"` and `"eslint:all"` strings no longer accepted in flat config](#string-config)
+* [`varsIgnorePattern` option of `no-unused-vars` no longer applies to catch arguments](#vars-ignore-pattern)
 
 ### Breaking changes for plugin developers
 
@@ -236,6 +237,25 @@ export default [
 
 **Related issue(s):** [#17488](https://github.com/eslint/eslint/issues/17488)
 
+## <a name="vars-ignore-pattern"></a> `varsIgnorePattern` option of `no-unused-vars` no longer applies to catch arguments
+
+In previous versions of ESLint, the `varsIgnorePattern` option of `no-unused-vars` incorrectly ignored errors specified in a `catch` clause. In ESLint v9.0.0, `varsIgnorePattern` no longer applies to errors in `catch` clauses. For example:
+
+```js
+/*eslint no-unused-vars: ["error", { "caughtErrors": "all", "varsIgnorePattern": "^err" }]*/
+
+try {
+    //...
+} catch (err) { // 'err' will be reported.
+    console.error("errors");
+}
+
+```
+
+**To address:** If you want to specify ignore patterns for `catch` clause variable names, use the `caughtErrorsIgnorePattern` option in addition to `varsIgnorePattern`.
+
+**Related issue(s):** [#17540](https://github.com/eslint/eslint/issues/17540)
+
 ## <a name="removed-context-methods"></a> Removed multiple `context` methods
 
 ESLint v9.0.0 removes multiple deprecated methods from the `context` object and moves them onto the `SourceCode` object:

lib/rules/no-unused-vars.js

@@ -141,7 +141,7 @@ module.exports = {
             } else if (defType === "Parameter" && config.argsIgnorePattern) {
                 type = "args";
                 pattern = config.argsIgnorePattern.toString();
-            } else if (defType !== "Parameter" && config.varsIgnorePattern) {
+            } else if (defType !== "Parameter" && defType !== "CatchClause" && config.varsIgnorePattern) {
                 type = "vars";
                 pattern = config.varsIgnorePattern.toString();
             }
@@ -623,9 +623,7 @@ module.exports = {
                             if (config.caughtErrorsIgnorePattern && config.caughtErrorsIgnorePattern.test(def.name.name)) {
                                 continue;
                             }
-                        }
-
-                        if (type === "Parameter") {
+                        } else if (type === "Parameter") {
 
                             // skip any setter argument
                             if ((def.node.parent.type === "Property" || def.node.parent.type === "MethodDefinition") && def.node.parent.kind === "set") {

tests/lib/rules/no-unused-vars.js

@@ -1132,6 +1132,16 @@ ruleTester.run("no-unused-vars", rule, {
             options: [{ caughtErrors: "all", caughtErrorsIgnorePattern: "^ignore" }],
             errors: [definedError("err", ". Allowed unused args must match /^ignore/u")]
         },
+        {
+            code: "try{}catch(err){};",
+            options: [{ caughtErrors: "all", varsIgnorePattern: "^err" }],
+            errors: [definedError("err")]
+        },
+        {
+            code: "try{}catch(err){};",
+            options: [{ caughtErrors: "all", varsIgnorePattern: "^." }],
+            errors: [definedError("err")]
+        },
 
         // multiple try catch with one success
         {